The Chandra X-Ray Observatory must operate in space because
A) X-rays are too dangerous to be allowed on the ground.
B) X-rays do not penetrate Earth's atmosphere.
C) X-ray telescopes require the use of grazing incidence mirrors.
D) It was built by NASA.
B
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An observer in the Northern Hemisphere takes a time exposure photograph of the night sky. If the illustration below depicts the photograph taken by the observer, which direction was the camera pointing?
a.
straight north
b.
straight east
c.
straight south
d.
straight west
e.
straight up, directly overhead
A molecule takes 3.0 seconds to diffuse across a membrane. If the thickness of the membrane is doubled, then how long does it take the molecule to diffuse across the thicker membrane?
A. 30 hours B. 24 hours C. 20 hours D. 18 hours E. 12 hours
The gravitational field is equivalent to:
a. the inertial mass. b. an accelerated frame of reference. c. an event horizon. d. a clock running slowly.
A really high-speed train moves in a direction parallel to its length with a speed that approaches the speed of light. The length of the train, as measured by a stationary observer on the ground,
A) decreases due to the motion. B) increases due to the motion. C) is not affected by the motion. D) approaches infinity.